Flat portions of a probe card flattened to have same vertical level with one another by compensating the unevenness of a substrate and each identical height needle being mounted on the corresponding flat portion through an adhesive

ABSTRACT

A probe card on which micro probe needles are arranged at high density and with high precision without need of a complicated structure or variation in needle height. A probe card  1  installed in a wafer tester includes a board  2  having a wiring pattern for transmitting a test signal to be impressed on a wafer under test, a built-up board  10  formed on the surface of the board  2 , a comb-shaped silicon-made probe needle  20  arranged on the built-up board  10  and connected to the surface wiring pattern  11 , and a flat portion  12  formed by plating on the surface wiring pattern  11  on the built-up board  10  and having a surface flattened by polishing. The probe needle  20  is loaded on the flat portion  12  and thus mounted on the board  2.

TECHNICAL FIELD

The present invention relates to a probe card disposed in a wafer tester(wafer prober) for performing an electric property test of a wafer whichis not packaged.

Particularly, the present invention relates to a probe card and a methodof manufacturing the probe card in which probe needles to contactelectrodes of a wafer are formed to be fine using silicon, nickel andthe like and in which a flat portion is flattened with high precisionand formed on a substrate including the probe needles mounted/fixedthereon and in which micro probe needles can be arranged at high densityand with high precision without requiring any complicated structure orthe like or without any variation in needle height.

BACKGROUND ART

In general, a plurality of semiconductor device chips formed on a wafer(semiconductor substrate) are tested for electric properties of eachdevice and the like in a state of a wafer before cut into individualchips and sealed into packages, a so-called semi-finished product state.This testing of the wafer in the semi-finished product state isperformed using a wafer tester called a wafer prober provided with aprobe card including probe needles (probes) which contact electrodes ofthe wafer to apply test signals.

FIG. 13 is a front view schematically showing a wafer tester including aconventional probe card. As shown in the figure, the conventional wafertester includes a wafer base 104 on which a wafer 103 constituting atesting object is to be mounted, and a probe card 101 positioned abovethe wafer base 104.

The probe card 101 includes a board 102 constituted of a printed circuitboard or the like which transmits a predetermined test signal to beapplied to each chip on the wafer 103 and a plurality of probe needles120 arranged/fixed on the board 102.

The wafer base 104 is driven/controlled in a three-dimensional direction(arrow directions shown in FIG. 13) in such a manner that predeterminedelectrodes of the mounted wafer 103 contact the predetermined probeneedles 120 of the probe card 101.

In the conventional wafer tester constituted in this manner, when thewafer base 104 is driven/controlled, the probe needles 120 of the probecard 101 contact the predetermined chip electrodes on the wafer 103.Moreover, test signals are applied to the electrodes of the wafer 103from the tester via the board 102 of the probe card 101, and each devicechip on the wafer 103 is subjected to a predetermined electric propertytest.

Here, in the conventional wafer tester, as shown in FIG. 13, the probeneedles 120 disposed in the probe card 101 are constituted of needlesformed of metals such as tungsten and the like, and a so-calledcantilevered probe needle structure has been adopted in which a largenumber of metal needles are bent/formed into L-shapes, arranged on theboard 102 having a plane disc shape, and fixed by a resin 130.

As the cantilevered probe needle, the metal needle having a total lengthof about 30 to 50 mm is bent/formed in such a manner that a needleheight (arrow h shown in FIG. 13) on a tip side is about 10 mm. Evenwhen there is a fluctuation in the height of the needle contacting theelectrode of the wafer 103, the fluctuation can be absorbed within alimit of elasticity of the needle, for example, several μms. Moreover, aplurality of (e.g., several hundreds of) cantilevered probe needles areall arranged on the substrate, and bonded by an adhesive or the like bya manual operation.

However, a problem has occurred that the conventional probe cardincluding the cantilevered probe needles cannot cope with the testing ofhighly densified and miniaturized wafers in recent years. In recentyears, miniaturization and densification of semiconductor devices haveremarkably advanced, and even the electrode on each chip has a microsize and interval (e.g., the electrode has one side of about 60 μm to100 μm, and a pitch is about 100 μm to 200 μm).

In the conventional probe card, the cantilevered probe needle itself hasa diameter of about 250 μm, all the probe needles have been attached bythe manual operation, and therefore it has been impossible to attach alarge probe needles at micro intervals on the substrate. Therefore, inrecent years, the highly densified and miniaturized wafers have not beentested with the cantilevered probe card.

Additionally, in the cantilevered probe needle, there has been a problemthat high frequency characteristics are deteriorated because the totallength of the needle is about 30 to 50 mm.

Therefore, to solve the problem of the conventional probe card, aso-called membrane type probe card has been proposed in which aplurality of electrode bumps are formed on a thin film including apredetermined pattern wiring formed thereon and having flexibilityinstead of the cantilevered probe needles. Such a membrane type probecard is disclosed by Japanese Patent Application Laid-Open No. 1-128381(page 4, FIG. 12), Japanese Patent Application Laid-Open No. 5-215775(pages 3 and 4, FIG. 2), Japanese Patent Application Laid-Open No.7-007056 (pages 4 and 5, FIG. 1), and Japanese Patent ApplicationLaid-Open No. 8-083824 (pages 5 and 6, FIG. 3).

According to the membrane type probe card, fine processing of theelectrode bumps formed on the thin film is possible, and therefore ithas been possible to cope with the testing of the miniaturized andhighly densified wafers.

However, the membrane type probe card has required a large number ofcomplicated constituting elements such as a membrane including theelectrode bumps, a holding structure which holds the membrane, andpressurizing means for energizing the membrane toward a wafer side.

Therefore, the probe card and wafer tester have been complicated andenlarged, and manufacturing costs have also increased as compared withthe conventional cantilevered type.

The present inventor has realized that when silicon is etched or nickelplating or the like is used, it is possible to form a fine needle havinga length of about 1 mm to 2 mm, and fine probe needles can be formed athigh density and high precision without requiring the above-describedmembrane structure. However, thereafter it has been realized that evenwhen the fine probe needles can be formed with high precision, and whenthe fine probe needles are simply mounted on the substrate, the needleheights of the probe needles are not uniform by unevenness of thesubstrate.

In general, for example, in a printed circuit board, the unevenness inheight or flatness gently continues usually in a range of about 0.1 mmto 0.3 mm on the surface of the substrate. Therefore, when the fineprobe needles having lengths of about 1 mm to 2 mm are mounted on thissubstrate surface, fluctuations are generated in the needle heights bythe unevenness of the substrate. Additionally, the fluctuations cannotbe absorbed within the elasticity limit by the probe needles havingmicro needle tips unlike the conventional cantilevered needle.

Therefore, as a result of further intensive researches, the presentinventor has created a probe card of the present invention in which theproblem of the unevenness of the substrate is solved and micro probeneedles can be highly densely mounted.

That is, the present invention has been proposed to solve theabove-described problem of the related arts, and an object thereof is toprovide a probe card and a method of manufacturing the probe card inwhich probe needles to contact electrodes of a wafer are formed to befine using silicon, nickel and the like and in which a flattened flatportion is formed on a substrate including the probe needlesmounted/fixed thereon and in which fluctuations in needle heights areeliminated and micro probe needles can be arranged at high density andwith high precision without requiring any complicated structure or thelike.

DISCLOSURE OF THE INVENTION

A probe card of the present invention is disposed in a wafer tester. Theprobe card includes: a substrate having a wiring pattern which transmitsa test signal to be applied to a wafer constituting a testing object; aprobe needle disposed on the substrate and connected to the wiringpattern to contact an electrode of the wafer; and a flat portion whichis formed on the surface of the substrate and whose surface isflattened, the probe needle being mounted on the flat portion.

According to the probe card of the present invention constituted in thismanner, when the probe needle to contact the electrode of the wafer isformed, for example, of nickel, silicon and the like, fine needles eachhaving a needle length of about 1 mm to 2 mm can be formed with highprecision, and a plurality of needles can be formed at micro intervalsat high density. Moreover, the flattened flat portion is formed on thesubstrate on which the probe needle is to be mounted, and accordingly amounting surface of the probe needle can be formed into a flat surfacehaving a flatness of about 10 μm or less.

Accordingly, even when unevenness, difference of elevation or the likeexists on the surface of the substrate, fluctuations of needle heightsare eliminated, and it is possible to arrange and fix the micro probeneedles on the substrate.

Therefore, according to the present invention, the probe card includingthe probe needle formed to be fine with high precision can be realizedby a simple structure, and testing of the highly densified wafer inrecent years can be securely performed. Moreover, when the probe cardaccording to the present invention is disposed, a whole device isprevented from being enlarged or complicated without requiring acomplicated structure or the like unlike a conventional membranestructure, and there can be provided a wafer tester whose costs havebeen lowered.

Concretely, in the probe card of the present invention, the flat portioncan be constituted to be flattened by polishing its surface. Thus,according to the present invention, the flat portion of the surface ofthe substrate such as a printed circuit board can be flattened with highprecision by the polishing. Accordingly, a plating layer or the like isstacked on the surface of the substrate, and polished, so that the flatportion according to the present invention can be easily formed withhigh precision, and the probe card of the present invention can beinexpensively realized without requiring any expensive material orcomplicated device or the like. Here, the polishing can be performed bylap polishing for use in manufacturing, for example, wafers or DVDdiscs.

Moreover, in the probe card of the present invention, the substrate canbe constituted to include a built-up portion formed on the surface, andthe flat portion is formed on the surface of the built-up portion of thesubstrate. Thus, according to the present invention, the flat portionaccording to the present invention can be formed even with respect tothe substrate including the built-up portion. In general, for example,when the wiring pattern of the printed circuit board is highly densifiedat a pitch width of about 100 μm, a built-up board (built-up portion) isstacked/formed on the surface of the substrate. Moreover, in the presentinvention, the flat portion can also be formed on the substrateincluding the built-up portion, and the probe card can be more highlydensified and refined. Therefore, in the substrate including thebuilt-up portion, the wiring pattern on which the flat portion of thepresent invention is formed means the wiring pattern of the built-upportion. It is to be noted that, needless to say, the present inventioncan be applied to the substrate which does not include any built-upportion.

Furthermore, in the probe card of the present invention, the flatportion can be constituted to be formed along the wiring pattern on thewiring pattern. Thus, in the present invention, the flat portion of thepresent invention can be formed along the wiring pattern on the wiringpattern connected to the probe needles. Accordingly, for example, whenthe flat portion is constituted of a conductive member, the wiringpattern itself is flattened with high precision, and the probe cardaccording to the present invention can be realized without changing anyconstitution of the substrate or the probe needle. Moreover, when thewiring pattern is flattened in this manner, a mounting structure of theprobe needle is similar to that of a usual probe card which does notinclude any flat portion, the probe card of the present invention can beapplied as such to the existing tester, mounting step or the like, andthere can be provided a probe card superior in versatility.

Moreover, in the probe card of the present invention, the flat portioncan be constituted of a plating layer formed on the substrate. Thus, inthe present invention, the flat portion can be formed, for example, bynickel plating or the like. Furthermore, the surface of the platinglayer is polished or processed otherwise, and can be easily flattened.Accordingly, the flat portion according to the present invention can beeasily formed with high precision. Especially when the flat portion isconstituted of the plating layer having conductivity, the flat portionis formed in accordance with the wiring pattern of the substrate,accordingly the wiring pattern itself can be flattened with highprecision, and a mounting structure of the fine and high-precision probeneedle can be realized without changing any constitution of thesubstrate or the probe needle.

Furthermore, according to the probe card of the present invention, theflat portion can be constituted of a mask layer formed on the substrate.Thus, in the present invention, the flat portion can be formed by themask layer constituted, for example, of a metal mask, a mesh mask or thelike. Moreover, the surface of the mask layer is polished or processedotherwise, arid can be easily flattened. Accordingly, the flat portionaccording to the present invention can be easily formed with highprecision. Especially when the flat portion is constituted of the masklayer, the flat portion can be formed broadly in a plane form on thesurface of the substrate, and the mounting of the probe needle can befacilitated.

Additionally, in the probe card of the present invention, the flatportion can be constituted of a built-up layer formed on the substrate.Therefore, in the present invention, when the built-up layer (built-upportion) is disposed on the surface of the substrate, the built-up layeris polished, and accordingly the flat portion according to the presentinvention can be formed directly on the built-up layer. When thebuilt-up layer is directly polished to form the flat portion, the flatportion according to the present invention can be formed broadly in aplane manner on the surface of the substrate in the same manner as in acase where the flat portion is constituted of the mask layer. When theflat portion is formed directly on the built-up layer in this manner,the flat portion according to the present invention can be formed moreeasily and efficiently, and the whole probe card can be thinned andlightened.

Moreover, in the probe card of the present invention, the probe needleis formed separately from the substrate, and can be constituted to bemounted on the flat portion. Especially, the probe needle can beconstituted to include a base portion and a plurality of needle portionsprotruding from the base portion in a comb shape. The probe needle maybe constituted of silicon formed into a needle shape, and a conductivepattern formed on the surface of silicon. Therefore, according to thepresent invention, when silicon is etched, the probe needles which areseparate from the substrate can be formed to be fine with highprecision. Accordingly, the fine probe needles suitable for the probecard of the present invention including the flat portion can be easilyformed with high precision. Since the probe needle is formed in a combshape (finger shape) including a large number of fine needles, a largenumber of probe needles can be mounted on the substrate by oneoperation, an operation for mounting the probe needles can be remarkablyeasily performed, and the probe card according to the present inventioncan be easily and efficiently manufactured. It is to be noted that theprobe needles formed of silicon or the like separately from thesubstrate can be, needless to say, formed into individual needles. Evenin this case, needless to say, the needles are applicable to the probecard including the flat portion of the present invention.

On the other hand, in the probe card of the present invention, the probeneedle can be formed directly on the surface of the flat portion.Moreover, the probe needle can be plated/formed into a needle shape onthe surface of the flat portion. Therefore, according to the presentinvention, the high-precision fine probe needle can be formed directlyon the flat portion, for example, by nickel plating or the like. As theprobe needle by the plating, the fine plated needle can be easily formedwith high precision, when masking and plating are repeated a pluralityof times on the flat portion. Accordingly, the fine probe needlesuitable for the probe card of the present invention including the flatportion can be easily formed with high precision. When the probe needleis formed directly on the flat portion by the plating in this manner, aneed for an operation for mounting the needle onto the substrate orconnecting the needle to the wiring pattern can be obviated, and theprobe card according to the present invention can be easily andefficiently manufactured.

Moreover, according to the present invention, there is a method ofmanufacturing a probe card, in which the surface for mounting a probeneedle is flattened to form a flat portion on the surface of a substrateof the probe card including: the substrate having a wiring pattern fortransmitting a test signal to be applied to a wafer constituting atesting object; and a probe needle disposed on the substrate andconnected to the wiring pattern to contact an electrode of the wafer,the method comprising: a step of forming a mask on the substrate onwhich a predetermined wiring pattern is formed; a step of forming anopening at a predetermined position of the mask; a step of plating theopening; and a step of polishing and flattening the surface of the mask.The method further comprises: a step of peeling the mask after the stepof polishing and flattening the surface of the mask. Therefore,according to the present invention, the flat portion according to thepresent invention can be easily formed on the wiring pattern of thesubstrate or in another desired position with high precision by masking,patterning, plating and the like. Moreover, the surface of the flatportion can be formed into a plane using the lap polishing and the like,so that the probe card according to the present invention can be easilymanufactured. It is to be noted that another method or step may also beused as long as unevenness, difference of elevation or the like of thesurface of the substrate is corrected and the flat portion having highflatness can be formed.

Furthermore, according to the present invention, there is provided amethod of manufacturing a probe card, in which the surface for mountinga probe needle is flattened to form a flat portion on the surface of asubstrate of the probe card including: the substrate having a wiringpattern for transmitting a test signal to be applied to a waferconstituting a testing object; and a probe needle disposed on thesubstrate and connected to the wiring pattern to contact an electrode ofthe wafer, the method comprising: a step of forming a built-up portionon the substrate on which a predetermined wiring pattern is formed; anda step of polishing and flattening the surface of the built-up portion.Therefore, according to the present invention, since the built-upportion (built-up layer) is formed on the surface of the substrate, andthe built-up portion is polished, the flat portion obtained by formingthe surface into the plane with high precision can be formed directly onthe built-up layer. When the flat portion is formed directly on thebuilt-up portion in this manner, it is possible to more easily andefficiently manufacture the probe card including the flat portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view schematically showing a wafer tester including aprobe card according to a first embodiment of the present invention;

FIG. 2 schematically shows a state in which the probe card according tothe first embodiment of the present invention is vertically reversed,(a) is a main part enlarged front view, and (b) is a perspective view;

FIG. 3 is a sectional view schematically showing a substrate and abuilt-up board constituting a base of the probe card according to thefirst embodiment of the present invention;

FIG. 4 schematically shows a built-up board on which a flat portion ofthe probe card is to be formed according to the first embodiment of thepresent invention, (a) is a schematic plan view, (b) is a sectional viewalong line A-A of (a) before the flat portion is formed, and (c) is asectional view along line A-A of (a) in which the flat portion isformed;

FIG. 5 schematically shows a state in which the probe card according toa modification of the first embodiment of the present invention isvertically reversed, (a) is a main part enlarged front view, and (b) isa perspective view;

FIG. 6 is an explanatory view showing one manufacturing step for theflat portion of the probe card according to the first embodiment of thepresent invention;

FIG. 7 is an explanatory view showing one manufacturing step for theflat portion of the probe card according to the first embodiment of thepresent invention;

FIG. 8 is an explanatory view showing a modification of themanufacturing step for the flat portion of the probe card according tothe first embodiment of the present invention;

FIG. 9 is an explanatory view showing a modification of themanufacturing step for the flat portion of the probe card according tothe first embodiment of the present invention;

FIG. 10 is an explanatory view showing another modification of themanufacturing step for the flat portion of the probe card according tothe first embodiment of the present invention;

FIG. 11 schematically shows a state in which the probe card according toa second embodiment of the present invention is vertically reversed, (a)is a main part enlarged front view, and (b) is a perspective view;

FIG. 12 schematically shows a probe needle formed on the probe cardaccording to the second embodiment of the present invention, (a) is aplan view, (b) is a front view, and (c) is a left side view; and

FIG. 13 is a front view schematically showing a wafer tester including aconventional probe card.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferable embodiments of a probe card according to the presentinvention will be described hereinafter with reference to the drawings.

First Embodiment

First, a first embodiment of the probe card according to the presentinvention will be described with reference to FIGS. 1 to 9.

[Wafer Tester]

FIG. 1 is a front view schematically showing a wafer tester including aprobe card according to a first embodiment of the present invention.

The wafer tester is a device for testing electric properties of eachdevice in a state of a wafer before a plurality of semiconductor devicechips formed on the wafer (semiconductor substrate) are cut intoindividual chips and sealed into a package, a so-called semi-finishedproduct state, and is also called a wafer prober. Concretely, as shownin FIG. 1, the wafer tester includes a wafer base 4 on which a wafer 3constituting a testing object is mounted, and a probe card 1 positionedabove the wafer base 4 according to the present embodiment.

The probe card 1 includes a plurality of probe needles 20 on a board 2constituted of a printed circuit board or the like which transmits apredetermined test signal to be applied to each chip on the wafer 3.Details of the probe card 1 will be described later.

The wafer base 4 is a mounting base of the wafer 3 which is a testingobject, and is driven/controlled in a three-dimensional direction (arrowdirections shown in FIG. 1) in such a manner that a predeterminedelectrode of the mounted wafer 3 contacts a predetermined probe needle20 of the probe card 1. Moreover, in the wafer tester, when the waferbase 4 is driven/controlled, the probe needle 20 of the probe card 1contacts the predetermined chip electrode of the wafer 3, and the testsignal is applied to the electrode of the wafer 3 from the tester viathe board 2 of the probe card 1. Accordingly, a predetermined electricproperty test is carried out with respect to each device chip formed onthe wafer 3.

[Probe Card]

FIG. 2 schematically shows a probe card according to the presentembodiment, (a) is a main part enlarged front view in a state in whichthe card is vertically reversed, and (b) is a perspective view in asimilar state. As shown in the figures, a probe card 1 includes a board2 and a built-up board 10 constituting a base and a probe needle 20.

The board 2 is constituted of a printed circuit board or the like, andis formed into a disc shape constituting a main body of the probe card1, and a wiring pattern (see a wiring pattern 2 a shown in FIG. 3) whichtransmits a test signal to be applied to the wafer 3 constituting atesting object is formed on the surface. The test signal is applied tothe wiring pattern from a signal generating unit or the like of thetester (not shown). Moreover, in the present embodiment, the built-upboard (built-up portion) 10 is formed on the surface of the board 2. Itis to be noted that the board 2 of the present embodiment has a steppedshape whose middle portion protrudes in a convex shape (see FIG. 1), andis formed in accordance with a structure on the side of the tester (notshown) to which the probe card 1 is to be attached, and the steppedshape is not especially indispensable. Therefore, needless to say, thesubstrate may also be formed into a usual flat plate shape.

FIG. 3 is a sectional view schematically showing the board 2 and thebuilt-up board 10 of the probe card 1 according to the presentembodiment. As shown in the figure, the built-up board 10 is amultilayered substrate (two layers in FIG. 3) in which the optionalnumber of insulating layers and conductive layers are alternatelystacked/formed on the surface of the board 2 constituting the base.

In general, the built-up board is a multilayered substratestacked/formed on the surface of the substrate, for example, in a casewhere the wiring pattern of the printed circuit board is highlydensified at a pitch width of 100 μm. In the present embodiment, thebuilt-up board 10 is disposed on the board 2 of the probe card 1, andaccordingly the probe card 1 is highly densified.

Moreover, a flat portion 12 whose surface is flattened is formed on thewiring pattern (see a surface wiring pattern 11 shown in FIG. 3) of thesurface of the built-up board 10.

FIG. 4 shows a plan view (FIG. 4( a)) and a sectional view (FIG. 4( b))of the built-up board 10 on which the flat portion 12 is formed. Asshown in the figure (b), the surface of the built-up board 10 (and theboard 2) has a shape in which gentle unevenness continues, and adifference of elevation usually exists in a range of about 0.1 mm to 0.3mm. Therefore, when the fine probe needle 20 is mounted as such on thesurface of the built-up board 10, fluctuations are generated in needleheight by the unevenness of the built-up board 10. Additionally, it isdifficult to absorb the fluctuation within an elasticity limit by themicro probe needle 20. To solve the problem, in the present embodiment,as shown in FIG. 4( c), the flat portion 12 flattened with highprecision is formed on the surface of the built-up board 10.

Concretely, the flat portion 12 according to the present embodiment isconstituted of a nickel plating layer plated/formed on the surface ofthe built-up board 10. Moreover, the surface of the nickel plating layeris polished and flattened to form the flat portion 12. When the flatportion 12 is formed by nickel plating or the like, and the surface ofthe plating layer is polished or processed otherwise, the high-precisionflattened flat portion 12 having a flatness of about 10 μm or less canbe formed (see FIGS. 6 and 7 described later). As a result, the surfacesof the flat portions 12 become the same vertical level with one anotheras shown in FIG. 4( c).

It is to be noted that the flat portion 12 may also be constituted of amask layer formed on the substrate surface instead of the plating layer(see FIGS. 8 and 9). Instead of forming the plating layer or the masklayer, the flat portion 12 may also be formed by directly polishing thebuilt-up board 10 on the board 2 (see FIG. 10).

Here, as a polishing method for flattening the flat portion 12, forexample, lap polishing may be used. The lap polishing is a type ofprecise finishing, and is a polishing method for use in a case where adegree of precision higher than that by grinding is required, and themethod is used, for example, in manufacturing wafers or DVD discs, orprecisely finishing optical glass products such as lenses and prisms.

Concretely, in the lap polishing, a lapping agent constituted of aprocessing solution (lapping solution) and abrasive grains is insertedbetween a tool called a lap and an object to be polished, the tool andthe object are slid/moved, and accordingly a satisfactory smooth surfaceis formed using an abrasive function between them.

As the lapping agent for use in the lap polishing, in general, theabrasive grains such as alumina powder, silicon carbide powder, anddiamond powder are blended with the lapping solution such as light oil,spindle oil, and machine oil for use. The lap polishing can be performedusing a lapping machine for exclusive use, and may also be performed bya manual operation.

By the use of this lap polishing, the flat portion 12 constituted of theplating layer of the present embodiment can be flattened with thehigh-precision flatness.

Moreover, in the present embodiment, the flat portion 12 is formed onthe surface wiring pattern 11 of the built-up board 10 in such a manneras to extend along the surface wiring pattern 11 (see FIG. 2( b)). Whenthe flat portion 12 is stacked/formed along the wiring pattern 11 inthis manner, a result similar to that in a case where the wiring patternitself is flattened by the flat portion 12 constituted of a conductivemember of nickel or the like is obtained. The probe card 1 according tothe present embodiment can be realized without changing any constitutionof the built-up board 10, board 2, or probe needle 20. Therefore, amounting structure of the probe needle 20 can be constituted in the samemanner as in the usual probe card 1 which does not include any flatportion 12, and the probe card 1 of the present embodiment can beapplied as such to the existing tester, mounting step and the like. Itis to be noted that the flat portion 12 is not restricted by a casewhere the section is formed along the wiring pattern 11 as shown in FIG.2(b). For example, when the flat portion 12 is constituted of a masklayer as described later, or when the flat portion 12 is formed directlyon the built-up board 10, the flat portion 12 can be formed in a planeform over the whole surface of the built-up board 10 (or the board 2)(see FIGS. 8 to 10).

Moreover, the probe needle 20 is mounted on the flat portion 12.

The probe needle 20 is a probe connected to the wiring pattern of theboard 2 via the built-up board 10 to contact the electrode of the wafer3 which is a testing object. As shown in FIG. 2, the probe needle 20 ofthe present embodiment is formed separately from the board 2 (and thebuilt-up board 10), mounted on the flat portion 12, and bonded by anadhesive 23 or the like. Concretely, the probe needle 20 is formed intoa comb shape including a base portion 21, and a plurality of needleportions 22 protruding from the base portion 21.

The base portion 21 connects the plurality of needle portions 22 to oneanother, and the bottom surface of the base portion is formed in such ashape that the probe needle 20 rises at a predetermined angle from thesurface of the built-up board 10. A space filled with the adhesive 23for bonding is formed on the side of the bottom surface of the baseportion.

The plurality of needle portions 22 are formed to protrude in a combshape (finger shape) from the base portion 21, and concretely severalhundreds of needle portions 22 each having a total length of about 1 mmto 2 mm are formed. Moreover, the needle portions 22 protrude from thesurface of the built-up board 10, and accordingly the probe needle 20having a needle height (arrow h shown in FIG. 1) of 1 mm or less isobtained.

When the probe needle 20 is formed into the comb shape including a largenumber of fine needle portions 22 in this manner, a large number ofprobe needles (needle portions 22) can be mounted on the board 2(built-up board 10) by one operation. It is to be noted that, needlessto say, the number or needle lengths of needle portions 22 may beappropriately changed in accordance with the number of electrodes of thewafer 3 constituting the testing object, the wiring pattern of the board2 or the built-up board 10 on which the portions are to be mounted andthe like.

In the present embodiment, silicon is etched to form the probe needle20. Concretely, the opposite surfaces of the silicon wafer are formedinto predetermined shapes (needle shapes constituting the comb shape inthe present embodiment) by the etching in the same manner as in the usein a method of manufacturing semiconductors. Moreover, a silicon oxidefilm is formed as an insulating layer on the surface of a comb-shapedsilicon main body. Accordingly, each needle portion 22 is insulated.Furthermore, conductive patterns 22 a constituted of conductive metalsor the like are formed on the surfaces of the respective needle portions22 insulated by the silicon oxide film. When silicon is etched in thismanner, the comb-shaped probe needle 20 can be finely formed with highprecision separately from the substrate, and the fine probe needle to besuitably mounted on the flat portion 12 flattened with high precision asdescribed above can be easily formed with high precision.

Moreover, the probe needle 20 is mounted on the flattened flat portion12, bonded to the surface of the built-up board 10 by the adhesive 23,and connected to the surface wiring pattern 11 of the built-up board 10.As shown in FIG. 2, the probe needle 20 is connected to the surfacewiring pattern 11 of the built-up board 10 by bonding wires 24. Thebonding wires 24 are wires fixed onto the conductive patterns 22 a ofthe surfaces of the respective needle portions 22 and the surface wiringpattern 11 of the built-up board 10 by soldering or the like, andelectrically connect the conductive patterns 22 a of the needle portions22 to the surface wiring pattern 11 of the built-up board 10.Accordingly, the respective needle portions 22 of the probe needle 20are connected to the conductive patterns 2 a of the board 2 via thebuilt-up board 10, and test signals are applied to the electrodes of thewafer 3 from the tester.

It is to be noted that in the connection of the probe needle 20 to thesurface wiring pattern 11 of the built-up board 10, not only the bondingwires 24 shown in FIG. 2 but also other means such as the soldering andthe like may be used. FIG. 5 shows a modification of a connectedconfiguration of the probe needle 20 to the surface wiring pattern 11.As shown in the figure, the probe needle 20 may also be connected to thesurface wiring pattern 11 of the built-up board 10 by soldering(soldering portions 25 of FIG. 5). Even in this case, the probe needle20 can be electrically connected to the surface wiring pattern 11.Moreover, in the connection by the soldering portions 25, the bondingwires 24 can be omitted, and a connecting operation can be easily andefficiently performed. Any configuration may also be adopted in theconnection of the probe needle 20 to the surface wiring pattern 11 inthis manner, as long as the test signal to be applied to the wafer 3 istransmitted without any trouble.

[Method of Manufacturing Probe Card]

Next, a method of manufacturing a probe card will be described withreference to FIGS. 6 and 7, in which a flat portion 12 is formed on thesurface of the built-up board 10 according to the present embodimentconstituted as described above. FIGS. 6( a) to (d) and FIGS. 7( a) to(c) are explanatory views showing one manufacturing step for the flatportion of the probe card according to the present embodiment.

First, a built-up board 10 on which a predetermined wiring pattern 11 isformed is prepared (see FIG. 6( a)), and a mask 14 is formed on thesurface of the built-up board 10 (see FIG. 6( b)). Here, as the mask 14,a metal mask using metal foils such as copper, stainless, and nickel, ameshed mask by a resin fiber or a metal wire woven into a mesh and thelike are usable.

Next, the mask 14 is patterned to form openings 14 a (see FIG. 6( c)).In the present embodiment, the openings 14 a are formed in positionsfacing the surface wiring pattern 11 of the built-up board 10 along thesurface wiring pattern 11. Here, the mask 14 can be etched to patternthe openings 14 a into desired positions, shapes and the like.

Thereafter, the openings 14 a are plated with nickel (see FIG. 6( d)).

Accordingly, the flat portion 12 which is not flattened is formed.

Moreover, the surface of the mask 14 plated with nickel is polished andflattened (see FIG. 7( a)). Here, as the polishing method, as describedabove, the lap polishing is preferably used. After the polishing ends,the mask 14 is peeled (see FIG. 7 (b)). Accordingly, the flattened flatportion 12 is formed on the surface wiring pattern 11 of the built-upboard 10. Consequently, the surfaces of the flat portions 12 become thesame vertical level with one another as shown in FIGS. 7( a) and 7(b).

Moreover, a probe needle 20 can be mounted on the flat portion 12 (seeFIG. 7 (c)). The probe needle 20 mounted on the flat portion 12 isbonded by an adhesive 23, and is electrically connected to the surfacewiring pattern 11 of the built-up board 10 by bonding wires 24.

Accordingly, the manufacturing of the probe card 1 of the presentembodiment completes, in which the probe needle 20 protrudes by a needleheight (arrow h shown in FIG. 1) of 1 mm or less from the surface of thebuilt-up board 10. In this manner, according to the method ofmanufacturing the probe card of the present embodiment, the flat portion12 can be easily formed with high precision on the surface wiringpattern 11 of the built-up board 10 or in another desired position bythe masking, patterning, plating and the like. Moreover, the surface ofthe flat portion 12 can be flattened with high precision using the lappolishing or the like.

In the above-described manufacturing method, the mask 14 is used only informing the flat portions 12, and is peeled after the flattening by thepolishing is performed (see FIG. 7( b)), but a step of peeling the mask14 may also be omitted, and the mask 14 is left on the surface of thebuilt-up board 10 (or the board 2) to form the flat portion 12, and mayalso be used as a base of the probe needle 20. FIGS. 8( a) to (e) and 9are explanatory views showing manufacturing steps in a case where themask 14 is used as the flat portion 12.

As shown in these figures, when the mask 14 is used as the flat portion12, in the same manner as shown in FIGS. 6, 7, first a built-up board 10on which a predetermined wiring pattern 11 has been formed is prepared(see FIG. 8( a)), and the mask 14 is formed on the surface of thebuilt-up board 10 (see FIG. 8( b)).

As the mask 14, as described above, a metal mask using metal foils suchas copper, stainless, and nickel, a mesh mask by a resin fiber or ametal wire woven into a mesh and the like are usable.

Next, the mask 14 is patterned by etching to form an opening 14 a (seeFIG. 8( c)). As shown in FIG. 8, unlike FIG. 6 described above, theopenings 14 a do not have to be formed along the surface wiring pattern11 of the built-up board 10, and the opening may be formed in at least apart of the surface wiring pattern 11 in such a manner as to beconductible. When the opening 14 a is plated with nickel, a conductivelayer 11 a is formed in such a manner that the surface wiring pattern 11electrically conducts to the surface of the mask 14 (see FIG. 8( d)).

The surface of the mask 14 on which the conductive layer 11 a is formedin this manner is polished and flattened (see FIG. 8( e)). It is to benoted that as a polishing method, the lap polishing is preferably usedin the same manner as in FIG. 7 described above.

Accordingly, the flat portion 12 obtained by flattening the mask 14 (andthe conductive layer 11 a) is formed on the surface of the built-upboard 10. Moreover, the probe needle 20 can be mounted on the flatportion 12 constituted of the mask 14 in this manner (see FIG. 9). Theprobe needle 20 mounted on the flat portion 12 is bonded by the adhesive23, and is connected to the conductive layer 11 a which conducts to thesurface wiring pattern 11 of the built-up board 10 by the bonding wires24.

Accordingly, the manufacturing of the probe card 1 of the presentembodiment using the mask 14 as the flat portion 12 completes. When theflat portion 12 is constituted of the mask 14 in this manner, as shownin FIG. 9, the flat portion 12 is formed into a plane shape over thewhole surface of the built-up board 10 (or the board 2).

Even when the flat portion 12 is constituted by the flattening withoutpeeling the mask 14, the flat portion 12 flattened with high precisioncan be easily formed, and the high-precision probe card can be easilyobtained in the same manner as in the manufacturing method shown inFIGS. 6, 7. It is to be noted that the flat portion 12 constituted ofthe mask 14 is not restricted by a case where the section is formed onthe surface of the built-up board 10, and the section may also be formeddirectly on the surface of the board 2 which does not include thebuilt-up board 10 in the same manner as in the flat portion 12constituted of the above-described plating layer.

Furthermore, instead of forming the flat portion 12 by theabove-described plating layer or mask layer, the flat portion may alsobe formed by directly polishing the built-up board 10 of the board 2.

FIGS. 10( a) to (e) are explanatory views showing manufacturing steps ina case where the flat portion 12 is formed directly on the built-upboard 10. As shown in the figures, when the flat portion 12 is directlyformed on the built-up board 10, first the built-up board 10 constitutedby alternately stacking insulating layers and conductive layers as shownin FIG. 3 is formed on the surface of the board 2 including apredetermined wiring pattern 2 a (see FIG. 10( a)) (see FIGS. 10( b) and(c)).

The wiring pattern 11 is formed on the insulating layer of the built-upboard 10 via a through-hole 10 a, and is connected to the wiring pattern2 a of the board 2. Moreover, the surface of the built-up board 10stacked/formed on the surface of the board 2 in this manner (one layerin FIG. 10) is polished and flattened (see FIG. 10( e)). As a polishingmethod, the lap polishing is preferably used in the same manner as inthe polishing of the above-described plating layer or mask layer.

Accordingly, the surface of the built-up board 10 is formed as the flatportion 12 flattened with high precision. Therefore, when the probeneedle 20 is mounted on the flat portion 12, and is electricallyconnected to the wiring pattern 11 via bonding wires or the like, theprobe needle 20 can be mounted directly on the flat portion 12constituted of the built-up board 10.

The flat portion 12 may also be formed directly on the built-up board 10in this manner. In this case, the flat portion 12 can be formed broadlyin a plane manner on the surface of the board 2 (built-up board 10) inthe same manner as in a case where the flat portion 12 is constituted ofthe above-described mask layer. Moreover, when the flat portion 12 isformed directly on the built-up board 10 in this manner, the flatportion 12 can be manufactured easily and efficiently, and further thewhole probe card can also be thinned and lightened.

As described above, by the probe card and the method of manufacturingthe probe card according to the present embodiment, when the probeneedle 20 contacting the electrode of the wafer 3 constituting thetesting object is formed, for example, by silicon, the fine needlehaving a needle length of about 1 mm to 2 mm can be formed with highprecision, and a plurality of needles can be formed at micro intervals.Moreover, the flat portion 12 flattened by the lap polishing or the likeis formed on the built-up board 10 of the board 2 on which the probeneedle 20 is to be mounted, and accordingly the surface for mounting theprobe needle 20 can be formed into a high-precision flat surface havinga flatness of about 10 μm or less.

Accordingly, the fluctuations of the needle heights can be eliminatedeven with the presence of the unevenness on the surface of the board 2,and the micro probe needle 20 having a needle height of 1 mm or less canbe disposed and fixed onto the board 2. Therefore, according to thepresent embodiment, the probe card 1 including the probe needle 20finely formed with high precision can be realized without requiring anycomplicated structure like a conventional membrane structure, and therecan be provided a wafer tester whose cost is low without enlarging orcomplicating the whole device.

Second Embodiment

Next, a second embodiment of a probe card according to the presentinvention will be described with reference to FIGS. 11 and 12.

FIG. 11 schematically shows a state in which the probe card according tothe second embodiment of the present invention is vertically reversed,(a) is a main part enlarged front view, and (b) is a perspective view.

FIG. 12 schematically shows a probe needle formed on the probe cardaccording to the present embodiment, (a) is a plan view, (b) is a frontview, and (c) is a left side view.

As shown in these figures, the probe card according to the presentembodiment is a modified embodiment of the above-described firstembodiment, and as the probe needle mounted on the flat portion, anickel-plated probe needle is used instead of the silicon-formed probeneedle formed into the comb shape in the first embodiment. Therefore,other constituting portions are similar to those of the firstembodiment, and the similar constituting portions are denoted with thesame reference numerals as those of the first embodiment in the figure,and detailed description is omitted.

As shown in FIG. 11, the probe card 1 of the present embodiment isconstituted in such a manner that the probe needle 20 is formed directlyon the surface of the flat portion 12.

In the present embodiment, the probe needle 20 is formed by the surfaceof the flat portion 12 plated into a needle shape with nickel.Concretely, when masking and plating are repeated on the flat portion 12a plurality of times, the probe needle 20 can be formed as shown in FIG.11.

First, a base portion 21 is formed for each surface wiring pattern 11 onthe flat portion 12, and thereafter needle portions 22 protruding inparallel with the surface of the board 2 (built-up board 10) are formedon each base portion 21. Furthermore, a protrusion 22 b which is acontact portion is formed on the tip of the needle portion 22.Accordingly, mutually independent probe needles 20 can be formeddirectly on the flat portion 12.

In this manner, in the probe needle 20 formed by the nickel plating, forexample, as shown in FIG. 12, the needle portion 22 has a total lengthof about 2 mm to 3 mm, and a total width of about 100 μm (see FIG. 12(a)), the base portion 21 has a height of about 150 μm (see FIG. 12( b)),and the protrusion 22 b on the needle portion tip has a height of about50 μm. This fine probe needles 20 can be formed and mounted on the flatportion 12 at a pitch of about 100 μm or the like. Accordingly, in thesame manner as in the first embodiment, the fine probe needle 20suitable for the probe card 1 including the flat portion 12 can beformed easily with high precision. In the present embodiment in whichthe probe needle 20 is formed directly on the flat portion 12 by theplating, a need for an operation for mounting the probe needle 20 or forconnecting the needle to the wiring pattern can be obviated, and theprobe card 1 can be manufactured easily and efficiently.

It is to be noted that the above-described probe card of the presentinvention is not restricted to only the above-described embodiments, andcan, needless to say, be variously modified in the scope of the presentinvention. For example, in the above-described embodiments, an examplein which silicon (Si), or nickel (Ni) is used as the material of theprobe needle has been described, but other materials may also be used aslong as the fine probe needle can be formed. Especially a materialhaving high elasticity is preferable in such a manner that the needlecontacting the wafer functions as a spring. For example, in addition tosilicon and nickel described above, beryllium copper (Be—Cu), tungstenand the like are usable.

Moreover, in the above-described embodiments, an example in which theflat portion is formed into the same shape as that of the wiring patternon the wiring pattern of the substrate (built-up board) has beendescribed, but a formed place or shape of the flat portion is notespecially restricted. Therefore, the flat portion may also be formedinto an optional shape in a place other than that on the wiring patternof the substrate, for example, in accordance with a size, shape and thelike of the probe needle to be mounted.

INDUSTRIAL APPLICABILITY

As described above, according to a probe card and a method ofmanufacturing the probe card of the present invention, a probe needlewhich contacts an electrode of a wafer is formed finely using nickel,silicon or the like, and a highly precisely flattened flat portion canbe formed on a substrate on which the probe needle is to be mounted orfixed.

Accordingly, a probe card can be realized in which micro probe needlesare arranged at high density and with high precision while fluctuationsof needle height are eliminated without requiring a complicatedstructure or the like.

1. A probe card disposed in a wafer tester, comprising: a substratehaving a wiring pattern which transmits a test signal to be applied to awafer constituting a testing object where a surface of the substrate hasunevenness in height; a plurality of probe needles each being formedseparately from the substrate and disposed on the substrate andconnected to the wiring pattern through a bottom end thereof while a topend thereof is free to directly contact electrodes of the wafer to betested, where each of the probe needles has a height identical to oneanother; and a plurality of flat portions each being formed on thesurface of the substrate and whose surface is flattened so that thesurfaces of the plurality of flat portions have the same vertical levelwith one another by compensating the unevenness of the substrate, thebottom end of the probe needle being mounted on the surface of thecorresponding flat portion through an adhesive.
 2. The probe cardaccording to claim 1, wherein the flat portion is flattened by polishingits surface thereby compensating the unevenness of the substrate.
 3. Theprobe card according to claim 1, wherein the substrate includes abuilt-up portion formed on the surface, and the flat portion is formedon the surface of the built-up portion of the substrate.
 4. The probecard according to claim 1, wherein the flat portion is formed on andalong the wiring pattern.
 5. The probe card according to claim 1,wherein the flat portion is constituted of a plating layer formed on thesubstrate.
 6. The probe card according to claim 1, wherein the flatportion is constituted of a mask layer formed on the substrate.
 7. Theprobe card according to claim 1, wherein the flat portion is constitutedof a built-up layer formed on the substrate.
 8. The probe card accordingto claim 1, wherein the probe needle includes a base portion and aplurality of needle portions protruding in a comb shape from the baseportion.
 9. The probe card according to claim 1, wherein the probeneedle is constituted of silicon formed into a needle shape, and aconductive pattern formed on the surface of silicon.